﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#nullable disable

using System.Collections;
using System.Diagnostics;
using System.Globalization;
using System.Reflection;
using System.Runtime.InteropServices;
using static Interop;

namespace System.Windows.Forms.ComponentModel.Com2Interop
{
    internal class Com2IManagedPerPropertyBrowsingHandler : Com2ExtendedBrowsingHandler
    {
        public override Type Interface => typeof(VSSDK.IVSMDPerPropertyBrowsing);

        public override void SetupPropertyHandlers(Com2PropertyDescriptor[] propDesc)
        {
            if (propDesc is null)
            {
                return;
            }
            for (int i = 0; i < propDesc.Length; i++)
            {
                propDesc[i].QueryGetDynamicAttributes += new GetAttributesEventHandler(OnGetAttributes);
            }
        }

        /// <summary>
        ///  Here is where we handle IVsPerPropertyBrowsing.GetLocalizedPropertyInfo and IVsPerPropertyBrowsing.   HideProperty
        ///  such as IPerPropertyBrowsing, IProvidePropertyBuilder, etc.
        /// </summary>
        private void OnGetAttributes(Com2PropertyDescriptor sender, GetAttributesEvent attrEvent)
        {
            object target = sender.TargetObject;

            if (target is VSSDK.IVSMDPerPropertyBrowsing)
            {
                Attribute[] attrs = GetComponentAttributes((VSSDK.IVSMDPerPropertyBrowsing)target, sender.DISPID);
                if (attrs != null)
                {
                    for (int i = 0; i < attrs.Length; i++)
                    {
                        attrEvent.Add(attrs[i]);
                    }
                }
            }
        }

        internal unsafe static Attribute[] GetComponentAttributes(VSSDK.IVSMDPerPropertyBrowsing target, Ole32.DispatchID dispid)
        {
            uint cItems = 0;
            IntPtr pbstrs = IntPtr.Zero;
            Oleaut32.VARIANT* pvars = null;

            HRESULT hr = target.GetPropertyAttributes(dispid, &cItems, &pbstrs, &pvars);
            if (hr != HRESULT.S_OK || cItems == 0 || pvars is null)
            {
                return Array.Empty<Attribute>();
            }

            ArrayList attrs = new ArrayList();

            string[] attrTypeNames = GetStringsFromPtr(pbstrs, cItems);
            object[] varParams = GetVariantsFromPtr(pvars, cItems);

            Debug.Assert(attrTypeNames.Length == varParams.Length, "Mismatched parameter and attribute name length");
            if (attrTypeNames.Length != varParams.Length)
            {
                return Array.Empty<Attribute>();
            }

            // get the types
            Type[] types = new Type[attrTypeNames.Length];
            for (int i = 0; i < attrTypeNames.Length; i++)
            {
                string attrName = attrTypeNames[i];

                // try the name first
                Type t = Type.GetType(attrName);
                Assembly a = null;

                if (t != null)
                {
                    a = t.Assembly;
                }

                if (t is null)
                {
                    // check for an assembly name.
                    //
                    string assemblyName = string.Empty;

                    int comma = attrName.LastIndexOf(',');

                    if (comma != -1)
                    {
                        assemblyName = attrName.Substring(comma);
                        attrName = attrName.Substring(0, comma);
                    }

                    string fieldName;
                    int lastDot = attrName.LastIndexOf('.');
                    if (lastDot != -1)
                    {
                        fieldName = attrName.Substring(lastDot + 1);
                    }
                    else
                    {
                        // somethings odd
                        Debug.Fail("No dot in class name?");
                        continue;
                    }

                    // try to get the field value
                    if (a is null)
                    {
                        t = Type.GetType(attrName.Substring(0, lastDot) + assemblyName);
                    }
                    else
                    {
                        t = a.GetType(attrName.Substring(0, lastDot) + assemblyName);
                    }

                    if (t is null)
                    {
                        Debug.Fail("Failed load attribute '" + attrName + assemblyName + "'.  It's Type could not be found.");
                        continue;
                    }

                    Debug.Assert(typeof(Attribute).IsAssignableFrom(t), "Attribute type " + t.FullName + " does not derive from Attribute");
                    if (!typeof(Attribute).IsAssignableFrom(t))
                    {
                        continue;
                    }

                    if (t != null)
                    {
                        FieldInfo fi = t.GetField(fieldName);

                        // only if it's static
                        if (fi != null && fi.IsStatic)
                        {
                            object fieldValue = fi.GetValue(null);
                            if (fieldValue is Attribute)
                            {
                                // add it to the list
                                attrs.Add(fieldValue);
                                continue;
                            }
                        }
                        else
                        {
                            Debug.Fail("Couldn't load field '" + fieldName + "' from type '" + attrName.Substring(0, lastDot) + "'.  It does not exist or is not static");
                        }
                    }
                }

                Debug.Assert(typeof(Attribute).IsAssignableFrom(t), "Attribute type " + t.FullName + " does not derive from Attribute");
                if (!typeof(Attribute).IsAssignableFrom(t))
                {
                    continue;
                }

                Attribute attr = null;

                // okay, if we got here, we need to build the attribute...
                // get the initalizer value if we've got a one item ctor

                if (!Convert.IsDBNull(varParams[i]) && varParams[i] != null)
                {
                    ConstructorInfo[] ctors = t.GetConstructors();
                    for (int c = 0; c < ctors.Length; c++)
                    {
                        ParameterInfo[] pis = ctors[c].GetParameters();
                        if (pis.Length == 1 && pis[0].ParameterType.IsAssignableFrom(varParams[i].GetType()))
                        {
                            // found a one-parameter ctor, use it
                            // try to construct a default one
                            try
                            {
                                attr = (Attribute)Activator.CreateInstance(t, new object[] { varParams[i] });
                                attrs.Add(attr);
                            }
                            catch
                            {
                                // nevermind
                                Debug.Fail("Attribute " + t.FullName + " did not have a initalizer specified and has no default constructor");
                                continue;
                            }
                        }
                    }
                }
                else
                {
                    // try to construct a default one
                    try
                    {
                        attr = (Attribute)Activator.CreateInstance(t);
                        attrs.Add(attr);
                    }
                    catch
                    {
                        // nevermind
                        Debug.Fail("Attribute " + t.FullName + " did not have a initalizer specified and has no default constructor");
                        continue;
                    }
                }
            }

            Attribute[] temp = new Attribute[attrs.Count];
            attrs.CopyTo(temp, 0);
            return temp;
        }

        private static string[] GetStringsFromPtr(IntPtr ptr, uint cStrings)
        {
            if (ptr != IntPtr.Zero)
            {
                string[] strs = new string[cStrings];
                IntPtr bstr;
                for (int i = 0; i < cStrings; i++)
                {
                    try
                    {
                        bstr = Marshal.ReadIntPtr(ptr, i * 4);
                        if (bstr != IntPtr.Zero)
                        {
                            strs[i] = Marshal.PtrToStringUni(bstr);
                            Oleaut32.SysFreeString(bstr);
                        }
                        else
                        {
                            strs[i] = string.Empty;
                        }
                    }
                    catch (Exception ex)
                    {
                        Debug.Fail("Failed to marshal component attribute BSTR " + i.ToString(CultureInfo.InvariantCulture), ex.ToString());
                    }
                }
                try
                {
                    Marshal.FreeCoTaskMem(ptr);
                }
                catch (Exception ex)
                {
                    Debug.Fail("Failed to free BSTR array memory", ex.ToString());
                }
                return strs;
            }
            else
            {
                return Array.Empty<string>();
            }
        }

        private unsafe static object[] GetVariantsFromPtr(Oleaut32.VARIANT* ptr, uint cVariants)
        {
            var objects = new object[cVariants];
            for (int i = 0; i < cVariants; i++)
            {
                try
                {
                    using Oleaut32.VARIANT variant = ptr[i];
                    objects[i] = variant.ToObject();
                }
                catch (Exception ex)
                {
                    Debug.Fail("Failed to marshal component attribute VARIANT " + i, ex.ToString());
                }
            }
            try
            {
                Marshal.FreeCoTaskMem((IntPtr)ptr);
            }
            catch (Exception ex)
            {
                Debug.Fail("Failed to free VARIANT array memory", ex.ToString());
            }

            return objects;
        }
    }
}
